Suspend State

1. A method of managing a suspend state of a packet-switched service in a system which comprises a terminal and another peer, there being a packet-switched connection between the terminal and the other peer over which the terminal and the other peer transmit packets to each other, the terminal being able to use only either a circuit-switched service or a packet-switched service at the same time, wherein in a situation in which the terminal switches to the suspend state in the packet-switched service to use a circuit-switched service: a predetermined first packet is transmitted from the terminal to the other peer to prevent transmission of packets from the other peer to said terminal during the suspend state, wherein the transmission of packets from the other peer to the terminal is controlled by a transmission window size parameter, and the first packet indicates to the other peer a transmission window size parameter value zero to prevent transmission.

2. A method according to claim 1 , further comprising transmitting said first packet before switching to the suspend state.

3. A method according to claim 1 , wherein the switching to the suspend state by the terminal is a multi-stage process, and said first packet is transmitted during said process.

4. A method according to claim 1 , wherein the method comprises delaying the switching to the suspend state by the terminal to transmit said first packet.

5. A method according to claim 1 , wherein said packet-switched connection is a TCP/IP connection (Transmission Control Protocol/Internet Protocol) and said packets are TCP/IP packets.

6. A method according to claim 1 , further comprising transmitting more than one of said first packets to prevent transmission of the packets from the other peer.

7. A method according to claim 1 , wherein said transmission window size parameter value zero is value zero of an advertised window parameter.

8. A method according to claim 1 , wherein the method further comprises aborting transmission of packets by the terminal in a controlled manner as the terminal switches to the suspend state.

9. A method according to claim 8 , wherein the terminal comprises a retransmission timer and that retransmission of the packets by the terminal is aborted by switching said retransmission timer off.

10. A method according to claim 8 , wherein the terminal comprises a retransmission timer and that retransmission of the packets by the terminal is aborted by allowing the retransmission timer to expire and by delaying reacting to the expiry of the retransmission timer.

11. A method according to claim 10 , wherein on returning from the suspend state back to the packet-switched service the terminal reacts to the expiry of said retransmission timer by performing retransmission.

12. A method according to claim 10 , wherein said delaying of the reacting to the expiry of the retransmission timer means that retransmission of the packets is delayed.

13. A method according to claim 1 , wherein in a situation in which the terminal switches from said suspend state back to the packet-switched service: a predetermined second packet is transmitted from the terminal to said other peer to continue transmission of packets from the other peer to the terminal.

14. A method according to claim 13 , wherein said second packet indicates a second value of said transmission window size parameter to the second peer to continue transmission of packets from the other peer to the terminal.

15. A method according to claim 14 , wherein said second value of the transmission window size parameter differs from the value zero.

16. A method according to claim 13 , wherein said second packet is a TCP/IP packet.

17. A method according to claim 13 , wherein the terminal, on switching from the suspend state back to the packet-switched service, returns to normal packet transmission operation.

18. A method according to claim 13 , further comprising transmitting more than one of said second packets.

19. A method according to claim 9 , wherein on returning from the suspend state back to the packet-switched service the terminal switches its retransmission timer on.

20. A terminal for managing a suspend state of a packet-switched service in a system which comprises a terminal and another peer, the terminal being arranged to communicate with said other peer on a packet-switched connection over which the terminal is arranged to transmit and receive packets, the terminal being able to use only either a packet-switched service or a circuit-switched service at the same time, wherein the terminal comprises: means for transmitting a predetermined first packet to the other peer in a situation in which the terminal switches to the suspend state in a packet-switched service to use a circuit-switched service, said first packet including information for preventing transmission of packets from the other peer to said terminal during the suspend state, wherein said information included in the first packet comprises a transmission window size parameter value zero to prevent transmission.

21. Software for a terminal for managing a suspend state of a packet-switched service in a system which comprises said terminal and another peer, the terminal being arranged to communicate with said other peer on a packet-switched connection over which the terminal is arranged to transmit and receive packets, the terminal being arranged to be able to use only either a packet-switched or a circuit-switched service at the same time, wherein the software comprises a program code: for transmitting, a predetermined first packet from the terminal to the other peer in a situation in which the terminal switches to the suspend state in the packet-switched service to use a circuit-switched service, said first packet comprising information for preventing transmission of packets from the other peer to said terminal during the suspend state, wherein said information included in the first packet comprises a transmission window size parameter value zero to prevent transmission.